Secondary batteries include nickel cadmium, nickel hydride, nickel zinc, lithium secondary batteries, and the like, and the typical battery is the lithium secondary battery.
A lithium oxide and a carbon material are widely used as a positive active material and a negative active material of the lithium secondary battery, respectively. The lithium secondary battery includes an electrode assembly in which positive and negative plates respectively coated with the positive active material and the negative active material are disposed with a separator interposed therebetween and an exterior material that seals and accommodates the electrode assembly with an electrolyte and can be classified into a can type secondary battery and a pouch type secondary battery according to the shape of the exterior material. In the present specification, a single secondary battery can be referred to as a battery cell.
When the secondary batteries are used for medium and large equipment such as vehicles or power storage systems, many battery cells are electrically connected to each other to form a battery module or a battery pack to increase capacity and output.
To form battery modules or battery packs in which the plurality of battery modules are connected, various coupling elements or cooling devices are required. Accordingly, such coupling elements or cooling devices lead to an increase in manufacturing cost, volume, and weight of the battery modules or the battery packs and lead to a decrease in output for the increased volume and weight.